Replication Based on Paxos

Synonyms

Consensus; State machine replication

Definition

Paxos is a consensus protocol designed for state machine replication in asynchronous environments subject to crash failures. State machine replication is a technique to increase the availability of a service by replicating the service in multiple replicas and regulating how client commands are propagated to and executed by the replicas: every non-faulty replica must receive and execute every command in the same order. State machine replication provides strong consistency, that is, from the perspective of the clients, the behavior of a service implemented by replicated servers is no different than the behavior of the service when implemented by a single server. Paxos ensures that commands submitted by the clients are delivered to the replicas in the same total order, despite the crash of some replicas.

Historical Background

State machine replication, sometimes called active replication, was introduced in [6] for environments in...